Lamivudine is a common name of the chemical compound 4-amino-1-[(2R,5S)-2-(hydroxymethyl)-1,3,-oxathiolan-5-yl]-1,2-dihydropyrimidin-2-one and has the chemical structure shown in FIG. 1. The free base form of lamivudine is known to be efficacious as an active pharmaceutical ingredient for the treatment of viruses, such as hepatitis, particularly hepatitis B, and HIV, and is marketed for those purposes in the United States under the names ZEFFIX®, HEPTOVIR®, EPIVIR, and EPIVIR-HBV®.
In drug development, it can be necessary to produce a compound to enable one or more formulations containing the compound to meet targeted pharmaceutical requirements and specifications. Crystalline forms of an active pharmaceutical ingredient can be used to control important physiochemical properties such as hygroscopicity, physical and chemical stability, solubility, bioavailability, melting point, purity, particle size, bulk density, flow properties, polymorphic content, and other properties. In addition, salts of active pharmaceutical ingredients, particularly salts with specific crystalline forms, can also provide control over such properties. Thus, there is a need for crystalline forms of lamivudine salts. The present disclosure fulfills these needs and provides further related advantages.